Engine starter drive



Sept. 9, 1952 Y. SEKELLA ENGINE STARTER DRIVE Filed sept. 26, 194e 2SHEETS- SHEET 1 W1TNESS= N I BY @Z5/15%@ A TORNEI Patented Sept. 9, 19522,609,696 y Yenclin: smeren nmvnv Youston .Sekella, Elmira, 'N'. Y.,assigner to Bendix Aviation Corporation, a corporation of DelawareApplicationSeptember-26, 1946, Serial No. 699,410

8 Claims.Y

'Itihe present invention .relates .to engine. starter drives vand moreparticularly to automatically engageable starter vgearing incorporating`a Irics tion clutch. I

It is an object of the present ;1nvent1on to prov-ide a novel enginestarter `drive.incorporating a'friction'clutch which is normallyalightlyloaded, the cranking load being applied progressively without severeshock.

It is another object to provide such a device in which the load capacityof the clutch 1s positively limited so as to prevent the application ofabnormal or shock loads to the elements of the drits a further object toprovide such .a device in which engagement of thegdrive is cushioned b5'the Ylightly. loaded clutch.

AItis another `object to provide sucha `device in `which thekineticenergy ofthe parts at the time of disengagement is dissipatedbysiippageor the` clutch so as to prevent any tendency for the parts to `reboundtoward operative position.

Further objects and advantages will .be .apparent from the followingdescription teiten in connection with the accompanyingdrawing. in

which:

'Fig `1 is a side elevation partly broken away and in, sectionl of onepreferred embodiment of the invention showing `theparts in idlepositlon;

Fig. 2 is a, similar view showing the parts 1n driving position; h

Fig. `3 is a similar view showing the parts in the positions assumed incase of tooth abutment between the drive pinion and engine gear m themeshing operation;

Eiei` is a side elevation partly in section of a second `embodin'xent ofthe 4invention intended `for heavy duty installations; I

. Fig.` 5 is a similar view. of a third embodiment of the; invention,alsoof theheavy-duty type;

and f y I Fig..A isvfa detail in. insrspectiyeV of the control nut andclutch actuating member of Fig. 4,'

In Fig. 1 ofthe drawing, there is illustrated a power shaft I which maybe the extended varmas ture shaft` of a. starting motor, the outer endof which isy preferably support-edl in an outboard bearing 2 which maybe attached to Athe frame oi the starting motori A sleeve `3 isnxed onthe power shaft as by means of afkey 4. and pin v5,

said sleeve having a reduced portion` 6. forming Y ajshoulder 1, onwhichportion a screw shaft 84 is slidably ourna-lled.` I .A stopnut vil is:fixed on the end of thesleeve `so as to corinne thescrew shaftthcreonyanda thrust-washer I0 isi-seated .on the- Sleeve lagainsttheshoulder l, .to .limit the lone' tudinal movement of the screwsha-ft. I

A pinion II is slidably journalled on the power s shaft I for movementinto and out of mesh with a'gear I2 of the engine `tobe started.A'control nut I31isthreaded on'the screw shaft 81 and vis rigidlyconnected to the `pinion by means `of abarrel member H xed at its endsto the control nut and Vpinion as indicated at l5 and I6 respec tively.

Means for actuating the screw shaft from-the' power shaft is providedcomprising a. second'barrel member II iixed `as indicated at I8tothescrew shaft and provided with a series .ofaslxlvtsl I9 in which aplurality of driven clutch discsZI arespiined. The sleeve `3 is providedwith splines 22 on which a plurality of driving clutch discs 23y areslidably mounted, and means comprising compression springs V2li areprovided within the barrel for compressing :the clutch discs betweenpressure plates 25 and 26 splinedv to the barrel and the sleeve 3respectively,

In the operation of this embodiment of the invention,l starting with theparts in the posh tions illustrated in Fig. i, rotationoi the Apowershaft I by the starting motor is transmitted through the sleeve 3,clutch 23, 2|., and barrel I1 to the screw shaft 8 which accordinglycauses` torque can be transmitted therethrough to crankV theA engine.The compression of the clutch springs 24 is limited by the thrust washerIiiV so as to prevent the torque capacity of the clutch from exceeding apredetermined maximum,-

thereby protectingl the drive from excessive loads by permitting .theclutch to slip. AThe overrun-j ning of the pinion II when the engine.starts, assisted by the anti-drift spring 20, causes the parts to bereturned to idle position, with screw shaft B'bearing against stop nut9.

A thrust washer 21 is preferably interposedl between the end of thescrew shaft and the stop nut, having such thickness as to maintain'theclutch springs `2li under suitablelight compression. With thisarrangement, when the parts are thrown back to idle position, thelightly- Vloaded. clutch slips and dissipates the. kinetic.`

energy of the parta, and. thus; prevents any tendn 3 ency of the pinionto rebound into engagement with the engine gear.

If, during the meshing operation, tooth abutment should occur betweenthe pinion I I and engine gear I2, the arresting of the longitudinalmovement of the pinion will cause the screw shaft 8 to move to the leftas shown in Fig. 3, thus causing the clutch sp-rings 24 to compress theclutch discs 2|, 23 until the torque transmitted therethrough becomessufficient to rotate the screw shaft and with it the control nut I3 andpinion I so as to move the teeth of the pinion into proper registry withthe tooth spaces of the engine gear I2. The clutch springs 24 thereuponexpand and snap the pinion into initial mesh with the engine gearwhereupon the meshing and cranking operations proceed as usual.

4 nut causes the backing nut 5| thereon to compress the clutch springs48 until the clutch is sufliciently loaded to transmit cranking torque.whereupon the rotation of the power shaft is caused to drive the enginegear. When the engine starts, the acceleration of the pinion 35 by theengine gear 36 is transmitted to the control nut 38 thus causing it tooverrun the screw shaft and return the parts to idle position with theassistance of the anti-drift spring 52, the kinetic energy of the partsbeing dissipated by slippage of the clutch. If the shock load caused bythe engagement of the drive exceeds a predetermined maximum, the nut 38comes into engagement with the thrust washer 56, whereby the clutchsprings 48 cannot be further compressed, and the clutch slips. -Thecranking operation thus takes In Figs. 4 and 6 of the drawing, there isil1us f' trated an embodiment of the invention which is particularlyadapted for the larger or heavy duty type of engine starters. As thereshown, a power shaft 3| has a solid screw shaft 32 rigidly coupledthereto, the screw shaft having a' reduced smooth portion 33 on which ismounted a bearing sleeve 34. A pinion 35 is slidably journalled on thebearing sleeve for movement into and out of mesh with an engine gear 36,the meshing position vof the pinion being defined by a stop nut 31 fixedon the screw shaft adjacent its outer end.

Means for actuating the pinion from the screw shaft is providedcomprising a control nut 38 threaded on the screw shaft and providedwith external splines 39 on which a driving clutch member 4| is slidablybut non-rotatably mounted. A driven clutch member in the form of abarrel 42'is fixed as indicated at'43 to the pinion 35, and a pluralityof driving and driven clutch discs 44 and 45 are splined alternately tothe driving and driven clutch members, the discs being retained on thedriving clutch member 4| by suitable means such as a lock ring 46, andbeing retained within the barrel 42 by means of a sleeve 41, the edgesof which are crimped down on the barrel.

Aplurality of compression springs 48 are arranged to bear against therear face of the driving clutch member 4|, said clutch member beingpreferably provided with studs 49 acting as centering means for saidsprings; and a backing nut 5| for the springs is adjustably threaded onthe end of the control nut 38. The control nut 38 and driving clutchmember 4| are provided with radially extending lugs 53 and 54respectively as best shown in Fig. 6, and when said parts are telescopedas shown in Fig. 4, a split lock ring 55 is snapped on the assemblybetween the lugsv soY as to hold the parts inl assembled relation, andmaintain initial compression of the clutch springs 48 as determined byadjustment of the backing nut 5|. A thrust washer 56 is located on thescrew shaft against the bearing sleeve 34 to arrest the travel of thenut 38, and thus limit the compression of the clutch springs 48. Ananti-drift spring 52 is located between the pinion 35 and stop nut 31for normally maintaining the parts in idle position.

In the operation of this embodiment of the invention, rotation of thepower shaft 3l is transmitted to the screw shaft 32 which causes thecontrol nut 38 to traverse the clutch members and pinion to the rightuntil the pinion is fully meshed with the engine gear 36 and engages thestop' nut 31. Further translation of the control place quietly andwithout excessive shock or stress.

If, during the meshing operation, tooth abutment should occur betweenthe pinion 35 and the engine gear 36, compression of the clutch discs44, will take-.place when the longitudinal movement of the pinion isarrested, so that increased torque will be transmitted to the pinion toindex it into proper registry with the tooth spaces of the engine gear.The expansion of the clutch springs 48 then snaps the pinion into meshwith the engine gear and meshing andcranking proceed as usual.

In Fig. 5 of the drawing, there is illustrated a form of heavy dutydrive in which the yielding clutch connection is interposed between thescrew shaft and the power shaft instead of being between the control nutand pinion. As there shown, a power shaft 6| vhas a solid extensionshaft 62 keyed thereon as indicated at`63, and the extension shaft isprovided with a reduced portion 64 on which is slidably journalled ascrew shaft 65. A pinion 66 is threaded on the screw shaft for movementinto and out of mesh with an engine gear'61, the meshing position of thepinion being dened by a stop nut 68 fixed on the end of the extensionshaft.

A barrel member 69 is fixedly mounted on the end of the screw shaft inany suitable manner, and a plurality of driving clutch discs 1| anddriven clutch discs 12 are splined respectively to the extension shaft62 and barrel 69, the clutch pack being retained in the barrel by meansof a sleeve 13 surrounding the barrel and enclosing the clutch discs. Anannular thrust plate 10 is seated on the extension shaft 62 against aplurality of radial lugs 86 thereon, so as to confine the clutch pack onsaid shaft.

A ring 14 of elastically deformable material such as rubber is mountedin the barrel to form' an elastic abutment for the clutch discs, and apressure ring 15 is slidably mounted on the extension shaft 62 adjacentthe open end of the barrel 69, and is pressed against the clutch discsby a plurality of springs 16, the initial pressure of which may beadjusted by means of a backingv plate 11 threaded on the end of theextension shaft 62.

In operation, rotation of the power shaft 6| is transmitted through theextension shaft 62 and`v traversal is stopped,l whereupon the screwshaft 65 moves backward thus compressing theclutch discs between therubber ring 14 and the clutch springs 1s. when thegloading of the clutchhas thus been suiciently increased, the rotation of the power shaft willbe transmitted therethrough to rotate the pinion 66 and thereby crankthe engine. If tooth abutment between the pinion and engine gear shouldtake place during the meshing operation, the clutch is tightened in thesame manner, to cause the pinion to be indeXed into proper meshingrelation with the engine gear, whereupon the clutch springs 'I6 expandand advance the pinion with the engine gear, and cranking takes place asusual.

When the engine starts, the pinion is returned to idle position where itis maintained by an antidrift spring 13, while the screw shaft 55 isheld in engagement with the stop nut S3 by the expansion of the rubberring 14.

It will be seen that in this embodiment of the invention also, theclutch discs are normally maintained under a preset initial pressurewhich is sufficient to accomplish the meshing operation and to prevent,by slippage of the clutch, the rebounding of the pinion when it isthrown out of mesh. The cranking load is applied -by the progressivetightening of the clutch, through the shuttling action of the screwshaft after the pinion engages the stop nut y68. In order to limit to apredetermined value the maximum torque delivered through the clutch,abutment means comprising one or more thrust rings 'i9 are mounted onthe smooth portion B4 of extension shaft 62 in position to limit theshuttling movement of the screw shaft.

Although but three embodiments of the invention have been shown anddescribed in detail, it will be understood that other embodiments arepossible and that various changes can be made in the design andarrangement of the parts without departing from the spirit of theinvention as set forth in the claims appended hereto.

What is claimed is:

1. In an engine starter drive a power shaft,

a pinion mounted for longitudinal movementv thereon into and out of meshwith a gear of an` engine to be started, means actuated by the powershaft for traversing and rotating the pinion including driving anddriven sets of spring-loaded frictionally-engaging clutch elen` ments, apair of inter-threaded members, and means slidably but non-rotatablyconnecting one of said inter-threaded members to one of said sets ofclutch elements, abutment means for deiining the operative position ofthe pinion, and means whereby longitudinal movement of said one threadedmember after the longitudinal movement of the pinion is arrested by theabutment causes the spring loading of the clutch to be graduallyincreased.

2. An engine starter drive as set forth in claim 1,` including-further,means for positively limiting the loading of the clutch elements.

3. In an engine starter drive a power shaft, a pinion mounted forlongitudinal movement thereon, means actuated by the power shaft fortraversing and rotating the pinion including driving and driven sets offrictionally engaging one of said sets of clutch elements, spring meansconnected with said one threaded member for compressing the clutchelements, abutment means for defining the operative position of thepinion, and means whereby rotation of the power shaft, after thelongitudinal movement of the pinion has been arrested by the abutment,causes relative longitudinal movement between the clutch elements andsaid one threaded member to increase the pressure of the spring means onthe clutch elements.

4. An engine starter drive as set forth in claim 3, including further,means for limiting the relative longitudinal movement of the clutchelements and threaded member in order to limit theload capacity of theclutch elements.

5. In an engine starter drive, a power shaft, a pinion mounted thereonfor longitudinal movement into and out of mesh with an engine gear,means for traversing and rotating the pinion including a splinedconnection, a friction clutch, and a threaded connection arranged inseries in the line of transmission of power, spring means for loadingthe friction clutch, and means including said threaded connection andsaid splined connection for compressing the spring means after thepinion has been traversed to fully meshed position, and means forlimiting the compression of the spring means so as to permit the clutchto slip when the torque exceeds a predetermined maximum.

6. An engine starter drive including a power shaft, Aa pinion slidablyjournalled thereon, a sleeve fixed to the power shaft, a screw shaftslidably journalled on the sleeve, a control nut on the screw shaft andmeans rigidly connecting the control nut and pinion, a stop nut. on thescrew shaft limiting the traversal of the control nut, a barrel member`fixed to the screw shaft, driving and driven clutch discs splinedalternately to the sleeve and barrel, an abutment on the sleeve limitinglongitudinal movement of the clutch discs, and springs in the barrelpressing the clutch discs against said abutment.

7. An engine starter drive as set forth in claim 6, including further,an abutment on the sleeve limiting longitudinal movement of the screwshaft in the direction to compress the springs.

8. In an engine starter drive, a screw shaft, a control nut threadedthereon, a pinion slidably journalled on the screw shaft, a drivingclutch member splined to the control nut, a driven clutch elements, apair of interfthreaded memi Number and a stop nut on the screw shaftlimiting lon-V` gitudinal movement cf the pinion.

YOU STON SEKELLA.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Name Date `1,403,022 Fornace, ga Jan. 1c, 19.22

